# SOLUTION: Twenty students randomly assigned to an experimental group receive an instructional program; 30 in a control group do not. After 6 months, both groups are tested on their knowled

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 Algebra: Probability and statistics Solvers Lessons Answers archive Quiz In Depth

 Question 467748: Twenty students randomly assigned to an experimental group receive an instructional program; 30 in a control group do not. After 6 months, both groups are tested on their knowledge. The experimental group has a mean of 38 on the test (with an estimated population standard deviation of 3); the control group has a mean of 35 (with an estimated population standard deviation of 5). Using the .05 level, what should the experimenter conclude? (a) Use the steps of hypothesis testing, (b) sketch the distributions involved, and (c) explain your answer to someone who is familiar with the t test for a single sample but not with the t test for independent meansAnswer by stanbon(57214)   (Show Source): You can put this solution on YOUR website!Twenty students randomly assigned to an experimental group receive an instructional program; 30 in a control group do not. ------------------------------------- After 6 months, both groups are tested on their knowledge. The experimental group has a mean of 38 on the test (with an estimated population standard deviation of 3); --------------- the control group has a mean of 35 (with an estimated population standard deviation of 5). -------------------- Using the .05 level, what should the experimenter conclude? (a) Use the steps of hypothesis testing, Ho: u(c)-u(e) = 0 Ha: u(e)-u(c) > 0 (tests a claim that the instruction helped) I ran a 2-Sample T test and got the following: test statistic: t = 2.6482 p-value: 0.0109 Conclusion: Since the p-value is less than 5%, reject Ho. The test supports the claim. ---------------------------------------------- (b) sketch the distributions involved, and (c) explain your answer to someone who is familiar with the t test for a single sample but not with the t test for independent means ------ I'll leave b and c to you. ============================== Cheers, Stan H.